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      <title>Redis搭建集群 - 交互式测验</title>
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      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Redis搭建集群 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，Redis 主从模式设计的主要目的是什么？",
    "options": [
      "解决单机 Redis 容量有限，进行数据分片。",
      "实现数据备份，并通过读写分离来分担主节点的读压力。",
      "监控主节点健康状况，并在其故障时自动进行故障转移。",
      "提供跨多个节点的事务一致性保证。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "主从模式的核心价值在于数据冗余和负载均衡。通过将主节点（Master）的数据复制到一个或多个从节点（Slave），实现了数据的备份，防止单点故障导致数据丢失。同时，可以将读请求转发到从节点，从而减轻主节点的读取压力。",
    "source": "文档中「Redis主从模式」部分",
    "hint": "文档提到：“主从复制是一种数据备份的方案...为了分担读压力，Redis支持主从复制。”"
  },
  {
    "question": "当一个从节点首次连接到主节点以建立复制关系时，会发生哪种数据同步方式？",
    "options": [
      "增量复制 (Incremental Replication)",
      "部分复制 (Partial Replication)",
      "全量复制 (Full Replication)",
      "延迟复制 (Delayed Replication)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "在主从关系初次建立时，从节点需要获取主节点当前所有的数据，这个过程被称为“全量复制”。主节点会执行BGSAVE生成RDB快照文件并发送给从节点。在此之后，主节点上发生的数据变更才会通过“增量复制”的方式同步。",
    "source": "文档中「Redis主从模式」-「主从复制过程」与「全量复制」部分",
    "hint": "思考一下，一个全新的从节点如何才能获得和主节点完全一致的初始数据？文档中描述：“首次建立复制，是全量复制的方式”。"
  },
  {
    "question": "Redis 哨兵模式 (Sentinel) 解决了主从模式的哪个核心痛点？",
    "options": [
      "主节点写入性能瓶颈问题。",
      "主节点数据量过大的存储问题。",
      "从节点无法写入数据的问题。",
      "主节点故障后无法自动进行故障转移，缺乏高可用性。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "在标准的主从模式下，如果主节点宕机，写服务会中断，需要人工介入才能将一个从节点提升为新的主节点。哨兵模式通过引入一个独立的监控进程（哨兵），能够自动检测主节点故障，并从从节点中选举出新的主节点，从而实现了自动故障转移和高可用性。",
    "source": "文档中「Redis哨兵模式」部分",
    "hint": "文档开头就指出：“主从模式的弊端就是不具备高可用性，当master挂掉以后, Redis将不能再对外提供写入操作, 因此sentinel应运而生。”"
  },
  {
    "question": "在哨兵模式中，当一个主节点被判定为“客观下线” (Objectively Down) 并触发故障转移时，需要满足什么条件？",
    "options": [
      "只需要一个哨兵认为主节点下线。",
      "所有哨兵都必须认为主节点下线。",
      "超过半数的哨兵认为主节点下线。",
      "由 `slave-priority` 值最高的哨兵节点决定。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "单个哨兵认为主节点宕机被称为“主观下线”。为了避免误判，只有当超过半数的哨兵都认为主节点宕机时，才会形成“客观下线”的共识，并由选举出的哨兵领导者来执行后续的故障转移流程。这是分布式系统中达成共识的典型做法。",
    "source": "文档中「Redis哨兵模式」-「哨兵选举过程」部分",
    "hint": "思考一下分布式系统如何避免单点误判。文档中提到：“一半以上哨兵认为主节点宕机后是客观下线”。"
  },
  {
    "question": "在哨兵执行故障转移，需要从多个从节点中选举一个新的主节点时，首要的选举标准是什么？",
    "options": [
      "选举优先级 (slave-priority) 最高的从节点。",
      "选举与原主节点断开时间最短的从节点。",
      "选举复制偏移量 (offset) 最大的从节点。",
      "选举 runid 最小的从节点。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "选举新主节点时，数据完整性是首要考虑因素。复制偏移量（offset）记录了从节点已同步的数据量。选择偏移量最大的从节点，意味着它拥有最接近原主节点的数据，可以最大限度地减少数据丢失。只有在偏移量相同的情况下，才会考虑优先级等其他因素。",
    "source": "文档中「Redis哨兵模式」-「哨兵选举过程」部分",
    "hint": "哪个指标最能体现从节点数据的“新鲜程度”？文档中选举规则的第一条是：“选举偏移量(决定了数据的最新程度)最大的从节点作为主节点”。"
  },
  {
    "question": "与哨兵模式相比，Redis Cluster 模式最核心的优势是解决了什么问题？",
    "options": [
      "实现了自动故障转移。",
      "简化了客户端的连接配置。",
      "通过数据分片解决了单机Redis的容量瓶颈，实现了水平扩展。",
      "增强了数据备份的可靠性。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "虽然 Cluster 模式也内置了类似哨兵的高可用机制，但它设计的初衷是为了解决数据量大到单台服务器无法存储的问题。通过引入哈希槽（hash slot）的概念，Cluster 模式能将数据自动分片到多个主节点上，从而实现存储容量的水平扩展。",
    "source": "文档中「Redis Cluster模式」部分",
    "hint": "文档描述：“cluster模式的出现就是为了解决单机Redis容量有限的问题，将Redis的数据根据一定的规则分配到多台机器。”"
  },
  {
    "question": "Redis Cluster 是如何确定一个给定的 key 应该存储在哪个节点上的？",
    "options": [
      "通过一个中心化的元数据节点进行分配。",
      "使用一致性哈希算法将 key 映射到节点。",
      "采用轮询方式依次存放到不同的主节点。",
      "通过计算 key 的 CRC16 值并对 16384 取模，将其映射到对应的哈希槽 (hash slot)。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "Redis Cluster 采用去中心化的哈希槽方案。它预设了 16384 个哈希槽，并将这些槽位分配给集群中的所有主节点。对于任何一个 key，集群会通过 `CRC16(KEY) % 16384` 的算法计算出它所属的槽位，然后客户端会被重定向到负责该槽位的节点进行操作。",
    "source": "文档中「Redis Cluster模式」-「Redis Cluster特点」部分",
    "hint": "文档中提到了一个关键数字和一个算法，它们共同决定了 key 的归属。原文是：“使用CRC16（KEY）&16384=slot得到他对应的hash slot”。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
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        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

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          optionsListEl.innerHTML = '';
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            return;
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            // 如果这道题已经回答过，恢复状态
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            userAnswers[currentQuestionIndex] = optionIndex;
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            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

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            nextBtn.style.display = 'block';
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            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
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                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
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        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
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            // 禁用所有选项的点击事件，并高亮正确/错误答案
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                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
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        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  